The gold-winning heptathlete said some talented youngsters are wary of training as they fear it will change their body shape and make them look unattractive and different to their friends.

Ennis told Radio Times that she too was concerned about weight training and had to be reassured by her coach that it would be worth it to win medals.

Ennis was revealed on Monday to be one of five women on the 12-strong shortlist for the BBC Sports Personality of the Year award.

Last year there was criticism that the judges failed to recognise achievements of women at all, but this year there are five women contenders including the rower Katherine Grainger and the Paralympic swimmer Ellie Simmonds are on the list, as well as the boxer Nicola Adams and cyclist Sarah Storey.

Ennis told the magazine: "It's important that girls aren't afraid of sport. I remember when I first started doing weight training,